Timothée Chalamet and Steve Carell play a drug addict and his father in “Beautiful Boy.” Photo: Amazon Studios

From the start, “Beautiful Boy” assumes a few things about the audience. The first is that an audience will automatically care about the central character, because his son is a drug addict. The second is that the audience will care about a young man, because he is a drug addict. The third is that the audience will care about the father, because he’s played by Steve Carell, and the fourth is that the audience will care about the drug-addicted son, because he’s played by Timothée Chalamet.

Not one of these assumptions turns out to be true — or even close to true. And the biggest part of the problem is the sheer difficulty of bringing this kind of story to the screen.

“Beautiful Boy” is based on the book of the same name by journalist and author David Sheff, about his own experience and that of his son, Nic, who became addicted to crystal meth. Books are meant for a certain audience and benefit from the personal voice of the author. And books carry with them an assumption of utility, that the experiences are being described for the edification of others. But these qualities don’t apply in a narrative feature made for a mass audience.

Maura Tierney and Steve Carell in “Beautiful Boy,” based on the memoirs by David Sheff and his son, Nic. Photo: Amazon Studios

The key word is “narrative.” A story about a drug addict doesn’t follow an effective narrative course — that is, it doesn’t build. It just repeats. A drug addict falls off the wagon, gets back on the wagon, falls off the wagon, gets on, falls off, gets on, falls off … and on and on. That’s the nature of drug addiction, and however much that might mean to the addict or to the loved ones involved, it’s a boring thing to watch from the outside, because the story can go nowhere, and it’s always the same.

Perhaps for that reason, “Beautiful Boy” tries something new, by not following the addict but the addict’s father. In the first scene, Carell, as David, goes to a psychiatrist, looking for information on crystal meth addiction. Before he can get much of an answer, the ultimate three-word movie buzzkill is flashed onto the screen — “One Year Earlier” — and we are thrust back in time to when Nic was beginning to show signs of a problem.

It doesn’t much matter, anyway. Within minutes, it becomes clear that the movie’s focus on David isn’t ideal. He’s not the one that the entire drama is happening to, and he can’t really grow, either. Over and over, it’s the same kind of action: He has to bail out his son. He has to rescue his son. He has to try to find his son. It gets to a point, quite soon, where David begins to seem more sap than Samaritan. That’s when the casting of Carell begins to have unintended consequences. Each time the phone rings and Carell reacts to the latest horror, the temptation is to laugh. After all, doesn’t he know what movie he’s in? What kind of phone call was he expecting?

Carell has a gentle aura, and Chalamet — though young and wispy — is a bit hard and unknowable. For purposes of drama, it might have been better if their natures were reversed, with the father being more distant (and then awakened to the son’s pain) and the son’s being so winning and adorable that the audience can’t help worrying about him. Instead, what happens is that we start hating the son on behalf of his father, which is precisely not the reaction that director Felix Van Groeningen was going for.

On the contrary, the movie is so insistent that we love this young man that it actually dredges up from beneath the floorboards of pop music history a recording of Perry Como singing “Sunrise, Sunset.” This is actually played on the soundtrack, without irony.

Meanwhile, the one potentially interesting person in the movie — Nic — remains as much a mystery at the end as he is at the beginning. How does an upper-class kid from Marin fall in love with crystal meth? Is it an emotional problem? A chemical problem? A cultural problem? Or is crystal meth so much fun that you’d better not do it ever? We don’t know. But at least the vagaries of time remain a subject for Perry Como’s eternal contemplation, so that’s something.